1  <grammar xmlns="http://relaxng.org/ns/structure/1.0">
 2  
 3  <define name="cell.content">
 4    <notAllowed/>
 5  </define>
 6  
 7  <start>
 8    <element name="table">
 9      <oneOrMore>
10        <element name="tr">
11          <oneOrMore>
12  	  <element name="td">
13  	    <ref name="cell.content"/>
14  	  </element>
15          </oneOrMore>
16        </element>
17      </oneOrMore>
18    </element>
19  </start>
20  
21  </grammar>